Feng Yi, Liu Qi, Lin Xiaocheng, Liu Jefferson Zhe, Wang Huanting
Department of Chemical Engineering and ‡Department of Mechanical and Aerospace Engineering, Monash University , Clayton, Victoria 3800, Australia.
ACS Appl Mater Interfaces. 2014 Nov 12;6(21):19161-7. doi: 10.1021/am505157w. Epub 2014 Oct 22.
Germanate nanowires/nanorods with different lengths were synthesized and used as additives for the fabrication of polymer composite membranes for high-flux water filtration. We for the first time demonstrated that at a small nanowire/nanorod loading (e.g., <0.5 wt % on the basis of poly(ether sulfone)), the length of germinate nanowires was a key parameter in determining their migration and diffusion in the polymer solution, and thus affecting polymer precipitation in the membrane formation process. In particular, short Ca2Ge7O16 nanowires with an average length of 138.7 nm and an average diameter of 12.7 nm, and Zn2GeO4 nanorods with an average length of 400 nm and an average diameter of 18.7 nm quickly diffused out of the membrane, leading to a higher pore density on the active layer in comparison with the pristine membranes. The addition of short Ca2Ge7O16 nanowires resulted in greater pore sizes than the addition of Zn2GeO4 nanorods because the out-diffusion of the former was faster than that of the latter. In contrast, the addition of long Ca2Ge7O16 nanowires with lengths of several tens to hundreds of micrometers and an average of 27.3 nm was not effective in promoting the pore formation because of partial embedment of nanowires. Poly(ether sulfone) composite membranes prepared by adding a small amount of Zn2GeO4 nanorods exhibited dramatically enhanced water permeation without losing rejection property. For example, the poly(ether sulfone) (PES) composite membrane prepared with 0.3 wt % Zn2GeO4 nanorods exhibited the highest flux, 1294.5 LMH, which was 3.5 times of the pristine (PES) membrane (384.2 LMH). Our work provides a new strategy for developing high-performance ultrafiltration membranes for practical industrial filtration applications.
合成了不同长度的锗酸盐纳米线/纳米棒，并将其用作添加剂来制备用于高通量水过滤的聚合物复合膜。我们首次证明，在低纳米线/纳米棒负载量下（例如，基于聚醚砜的含量小于0.5 wt%），锗酸盐纳米线的长度是决定其在聚合物溶液中迁移和扩散的关键参数，进而影响膜形成过程中的聚合物沉淀。具体而言，平均长度为138.7 nm、平均直径为12.7 nm的短Ca2Ge7O16纳米线以及平均长度为400 nm、平均直径为18.7 nm的Zn2GeO4纳米棒会迅速从膜中扩散出来，与原始膜相比，这导致活性层上的孔密度更高。添加短Ca2Ge7O16纳米线所形成的孔径比添加Zn2GeO4纳米棒时更大，因为前者的向外扩散速度比后者更快。相反，添加长度为几十到几百微米且平均直径为27.3 nm的长Ca2Ge7O16纳米线由于纳米线的部分嵌入，对促进孔形成并无效果。通过添加少量Zn2GeO4纳米棒制备的聚醚砜复合膜在不损失截留性能的情况下，水渗透性能显著增强。例如，添加0.3 wt% Zn2GeO4纳米棒制备的聚醚砜（PES）复合膜表现出最高通量，为1294.5 LMH，是原始（PES）膜（384.2 LMH）的3.5倍。我们的工作为开发适用于实际工业过滤应用的高性能超滤膜提供了一种新策略。
